Axial flow fan

ABSTRACT

The present invention provides an axial flow fan having conductive pins, each of which is configured to electrically connect a coil of a stator and a circuit board, and to hold a film conductor of the coil. In the conductive pin, one end is fixed to an electrical insulator covering a core stack of the stator, and the other end is electrically connected to the circuit board. The conductive pin is a quadrangular prism pin as a basic configuration and has, in at least a part of a portion exposed from the electrical insulator, a reduced diameter portion having no corners.

BACKGROUND

1. Technical Field

The invention relates to an axial flow fan having conductive pins with an improved structure for electrically connecting a coil and a circuit board as well as holding a film conductor of a coil.

2. Description of Related Arts

In a small axial flow fan such as a cooling fan, an outer rotor type of brushless motor is usually used as a rotation driving device for an impeller. In the outer rotor type of brushless motor, an armature having coils of a plurality of phases is used as a stator, and an exciter having a permanent magnet is provided as a rotor at an outer circumference of the stator.

A winding start end and a winding finish end of the coil of each phase are electrically connected to a circuit board through a conductive pin fixed to an insulator of a stator core. A jumper wire connecting coils to each other to form the coils of respective phases is held by being wound around the conductive pin.

As a technique related to an axial flow fan having a conductive pin, there has been disclosed one in which the conductive pin penetrates through and is held by at least one of first and second insulators holding a stator core in between, an end of a coil is electrically connected to one end of the conductive pin, and the other end of the conductive pin is inserted into a hole portion of a circuit board to electrically connect to the circuit board (for example, see Japanese Patent Laid-Open Publication No. 6-253482).

Further, there has been disclosed an axial flow fan in which front ends of a plurality of teeth are different in length in a circumferential direction and are formed unsymmetrically, and on the shorter side surface of the front end, a terminal holding portion with an implanted terminal pin is disposed in a close contact state. In this axial flow fan, a terminal of a coil is wound around one end of an end terminal, and the other end is electrically connected to a circuit board (for example, see Japanese Patent Laid-Open Publication No. 2011-182612).

SUMMARY

A conventional axial flow fan has employed a columnar or quadrangular prism-shaped conductive pin.

Since the columnar conductive pin has no corner, a film conductor wound around the conductive pin is less likely to be broken even if an unexpected load is applied to the conductive pin.

On the other hand, the frictional force of the columnar conductive pin having no corner is small, and thus a film conductor wound around the conductive pin is easily shifted. Thus, in a wire winding process, the film conductor wound around the conductive pin could not have been held depending on the wire diameter of the film conductor. When the film conductor having been wound up by an automatic winding machine is automatically cut, the film conductor is cut by utilizing the corner of the conductive pin. Therefore, in the columnar conductive pin, the film conductor cannot be automatically cut, and the film conductor should be cut manually.

Meanwhile, since the quadrangular prism-shaped conductive pin have corners, the film conductor having been wound up by using the automatic winding machine can be automatically cut. Further, the film conductor wound around the conductive pin can be held by the frictional force of the corners of the conductive pin.

On the other hand, since the quadrangular prism-shaped conductive pin have corners, if an unexpected load is applied to the conductive pin, the film conductor wound around the conductive pin may be broken by the corners of the conductive pin.

In the techniques of Japanese Patent Laid-Open Publication No. 6-253482 and Japanese Patent Laid-Open Publication No. 2011-182612, the disconnection of the film conductor is prevented by improving a connection structure of the conductive pin (terminal pin) and the film conductor of the coil. However, even if the techniques of Japanese Patent Laid-Open Publication No. 6-253482 and Japanese Patent Laid-Open Publication No. 2011-182612 are applied, failures due to a cross-sectional shape of the conductive pin may still occur.

The present invention provides an axial flow fan having conductive pins, each of which can reliably hold a film conductor of a coil, is not less likely to be broken even if an unexpected load is applied to the film conductor, and can be used in automatic cutting of the film conductor having been wound up.

In order to achieve the above object, an axial flow fan according to the present invention is provided with a stator having coils of a plurality of phases and a rotor having a permanent magnet. The axial flow fan has conductive pins, each of which is used for electrically connecting the coil and a circuit board and holding a jumper wire connecting the coils to each other.

In the conductive pin, one end is fixed to an electrical insulator covering a core stack of the stator, while the other end is electrically connected to the circuit board.

The conductive pin is a quadrangular prism pin as a basic configuration and has, in at least a part of a portion exposed from the electrical insulator, a reduced diameter portion in which no corners of the quadrangular prism pin exist.

According to the present invention, the conductive pin is a quadrangular prism pin as a basic configuration and has, in at least a part of a portion exposed from an electrical insulator, a reduced diameter portion in which no corners of the quadrangular prism pin exist . Since no corners of the quadrangular prism pin exist in the reduced diameter portion, the film conductor is less likely to be broken even if an unexpected load is applied to a film conductor of a coil.

Since the exposed portion other than the reduced diameter portion of the conductive pin has a quadrangular prism shape having corners, the film conductor wound around the conductive pin can be reliably held by the corners. Further, the film conductor having been wound up can be automatically cut by utilizing the corners of the exposed portion other than the reduced diameter portion of the conductive pin.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an axial flow fan according to an embodiment of the present invention;

FIG. 2 is a perspective view of a stator of the embodiment;

FIG. 3 is a perspective view of a conductive pin of the embodiment;

FIG. 4 is a perspective view of a state in which the conductive pin of the embodiment is fixed to an electrical insulator;

FIG. 5 is a perspective view of a state in which a film conductor is wound around the conductive pin of the embodiment;

FIG. 6A is a perspective view of a positional relationship of the conductive pins of the embodiment;

FIG. 6B is a view provided for explaining how the film conductor is wound around the conductive pin;

FIG. 6C is a view provided for explaining how the film conductor is wound around the conductive pin; and

FIG. 6D is a view provided for explaining how the film conductor is wound around the conductive pin.

DETAILED DESCRIPTION

Hereinafter, an axial flow fan according to an embodiment of the present invention will be described with reference to the drawings.

In the axial flow fan according to the present embodiment, a conductive pin is a quadrangular prism pin as a basic configuration and has, in at least a part of a portion exposed from the electrical insulator, a reduced diameter portion in which no corners of the quadrangular prism pin exist. According to the embodiment, it is possible to realize the axial flow fan having conductive pins, each of which can reliably hold a film conductor of a coil, is not less likely to be broken even if an unexpected load is applied to the film conductor, and can be used in automatic cutting of the film conductor having been wound up. In the embodiment, although the basic shape of the conductive pin is a quadrangular prism having an inner angle of 90°, it may be a triangular prism having an inner angle of less than 90° or a polygonal shape whose at least one corner has an inner angle of not more than 90°. A reduced diameter portion in the embodiment is a portion in which a maximum distance in a diameter direction of the conductive pin, other than the reduced diameter portion, is reduced and has a polygonal shape having an inner diameter more than 90° or a circular shape having no corners.

[Configuration of Axial Flow Fan]

A configuration of the axial flow fan according to the present embodiment will be first described with reference to FIGS. 1 to 5. FIG. 1 is a cross-sectional view of the axial flow fan according to the embodiment. FIG. 2 is a perspective view of a stator of the embodiment.

As shown in FIG. 1, an axial flow fan 1 is a blower which sucks air from one end in the axial direction of a rotating shaft 10 by rotation of impellers 20 attached to the rotating shaft 10, and discharges a fluid to the other end in the axial direction. The axial flow fan 1 has a simple structure and such a feature that although the static pressure is small, the air volume is large. The axial flow fan 1 is used for, for example, a cooling fan of an electronic device such as a server and a personal computer.

The axial flow fan 1 is provided with the impellers 20 attached to the rotating shaft 10, a motor 30 as a rotation driving device for the impeller 20, and a venturi casing (hereinafter referred to as “casing”) 40 surrounding the outer circumference in the diameter direction of the impeller 20.

The impeller 20 has a cupped hub portion 21 at its central portion. Blades 22 are attached radially and integrally around the hub portion 21. Each of the blades 22 is inclined with respect to the axial direction of the rotating shaft 10.

The motor 30 is provided in the hub portion 21. The motor 30 is provided with an outer rotor 50 as an exciter having a permanent magnet 51 and an inner stator 60 as an armature around which coils 61 having a plurality of phases are wrapped.

The rotor 50 includes a rotor yoke 52 having a shape of a two stage cup, the rotating shaft 10 press-fitted into a fitting-in portion 53 at the center of the rotor yoke 52, and the permanent magnet 51. The stator 60 includes core stacks 62 and coil 61 stored in slots 64 of the core stacks 62.

The rotor yoke 52 is fitted into the hub portion 21. The permanent magnet 51 is fixed to the inner circumferential surface of the rotor yoke 52 . The rotor yoke 52 has a function of closing magnetic field lines from the exciter and maximizing an electromagnetic induction effect of the permanent magnet 51. The rotor yoke 52 further has a function of preventing peripheral devices of the motor 30 from being affected by the electric field due to electromagnetic induction.

As a constituent material of the rotor yoke 52, an iron-based magnetic material such as an SC material is used; however, the invention is not limited to the exemplified material.

The rotating shaft 10 is rotatably supported by a bearing 70. The bearing 70 is fixed to an inner surface of a cylindrical bearing supporting portion 71. The bearing supporting portion 71 is formed at the center of a base portion 73.

A core stack 62 is fixed to an outer surface of the bearing supporting portion 71. The core stack 62 and the permanent magnet 51 of the rotor yoke 52 face each other with a gap therebetween.

The core stack 62 is formed by stacking a plurality of cross-ring shaped thin metal plates in a plate thickness direction. As a constituent material of the core stack 62, a silicon steel plate is preferred in order to realize both the performance and the cost. The metal plates of the core stack 62 are stacked while covering an insulating material such as varnish.

As shown in FIG. 1 or 2, teeth portions 63 (see FIG. 2) as protrusions used for wrapping the coil 61 therearound are formed in the core stack 62. The slot 64 as a convex used for storing the coils 61 is formed between the teeth portions 63 by partitioning the teeth portions 63. The teeth portions 63 and the slot 64 are evenly arranged along the circumferential direction of the core stack 62.

In the embodiment, in order to form coil groups having two phases, the teeth portions 63 and the slots 64 respectively provided at four portions are formed in the circumferential direction of the core stacks 62; however, the number of the phases of the coil 61 and each number of the teeth portions 63 and the slots 64 are not limited.

The inside of each of the slots 64 is covered with an electrical insulator 80. Namely, the periphery of the coil 61 wrapped around the teeth portions 63 is covered with the electrical insulator 80. As the electrical insulator 80, a synthetic resin is employed, for example.

A circuit board 90 is supported on the base portion 73 (see FIG. 1). A wiring pattern used for controlling the axial flow fan 1 is formed on the circuit board 90.

Conductive pins 100 are fixed to the electrical insulator 80 around the coils 61. A portion of the electrical insulator 80 corresponding to the teeth portion is provided with a pin fixing portion 81 used for fixing the conductive pin 100. The pin fixing portion 81 is raised toward outside in the axial direction. Although the pin fixing portions 81 of the embodiment are provided at three portions of the electrical insulator 80 corresponding to the teeth portions, the invention is not limited thereto.

[Structure of Conductive Pin]

Next, a structure of the conductive pin of the present embodiment will be described with reference to FIGS. 1 to 5. FIG. 3 is a perspective view of the conductive pin of the embodiment. FIG. 4 is a perspective view of a state in which the conductive pin of the embodiment is fixed to the electrical insulator. FIG. 5 is a perspective view of a state in which the film conductor is wound around the conductive pin of the embodiment.

As shown in FIGS. 1 and 2, one end of the conductive pin 100 is fixed to the pin fixing portion 81 of the electrical insulator 80. As shown in FIG. 1, the other end of the conductive pin 100 is inserted into a through-hole 91 of the circuit board 90 and electrically connected to the circuit board 90 by soldering 92, or the like.

As a constituent material of the conductive pin 100, a metal material having an excellent conductivity, such as copper, is used.

As shown in FIG. 3, the conductive pin 100 is a quadrangular prism pin as a basic configuration. The conductive pin 100 has, in at least a portion in the axial direction, a reduced diameter portion 120 in which no corners of the quadrangular prism pin exist. Namely, although the conductive pin 100 of the embodiment has, in an intermediate potion in the axial direction, the reduced diameter portion 120 in which the corners of the quadrangular prism pin are chipped off, the present invention is not limited thereto. The conductive pin 100 may have the reduced diameter portion 120 in a multistage fashion.

The reduced diameter portion 120 of the embodiment is formed by mechanically crushing the corners of the quadrangular prism conductive pin 100 with a tool such as a caulking machine. A method of the reduced diameter portion 120 formation in which the corners are chipped off not limited, and although the reduced diameter portion 120 may be formed by using other means such as cutting, the crushing processing is simple.

As shown in FIG. 4, one end of the conductive pin 100 is fixed by being embedded in the pin fixing portion 81 of the electrical insulator 80. While the conductive pin 100 is fixed to the electrical insulator 80, the conductive pin 100 is provided along the axial direction of the rotating shaft 10 (see FIG. 1).

The reduced diameter portion 120 having no corners of the conductive pin 100 is disposed in at least a part of a portion 110 exposed from the pin fixing portion 81 of the electrical insulator 80. The reduced diameter portion 120 of the embodiment is positioned at a base end (root) of the portion 110 exposed from the electrical insulator 80.

Since the reduced diameter portion 120 is positioned at the base end of the exposed portion 110 of the conductive pin 100, all the embedding sides of the conductive pin 100 may be formed by the reduced diameter portions 120. In order to prevent the conductive pin 100 from being slipped off from the electrical insulator 80, it is preferable that the reduced diameter portion 120 is formed at the intermediate portion of the conductive pin 100, as shown in FIG. 3.

As shown in FIGS . 2 and 5, the film conductor 65 of the coil 61 is held by being wound around the other end of the conductive pin 100. Winding of the film conductor 65 of the coil 61 is started from an exposed portion, other than the reduced diameter portion of the exposed portion 110 of the conductive pin 100, and finished at the reduced diameter portion 120 on the base end side. Alternatively, winding of the film conductor 65 of the coil 61 is started from the reduced diameter portion 120 on the base end side of the conductive pin 100 and finished at a portion 130 other than the reduced diameter portion on the front end side.

As the film conductor 65 of the coil 61, a coated copper wire such as an enamel wire is used, for example.

As shown in FIGS. 1 and 5, the conductive pin 100 is inserted into the through-hole 91 of the circuit board 90 in such a state that the film conductor 65 of the coil 61 is wound around the conductive pin 100 concerned, and the conductive pin 100 is electrically connected by the soldering 92, or the like.

[Operation of Axial Flow Fan]

Next, the operation of the axial flow fan 1 according to the present embodiment will be described with reference to FIGS. 1 and 6A to 6D.

As shown in FIGS . 1 and 2, in the axial flow fan 1 according to the embodiment, the winding start end and the winding finish end of the film conductor 65 of the coil 61 of each phase are wound around the exposed portion 110 of the conductive pin 100 fixed to the electrical insulator 80. The conductive pin 100 around which the film conductor 65 is wound is inserted into the through-hole 91 of the circuit board 90, and is electrically connected by the soldering 92, or the like.

A transition portion of the film conductor 65 connecting the coils to each other to form the coils 61 of respective phases is held by being wound around the conductive pin 100 in the same manner as above.

As shown in FIG. 5, the film conductor 65 is held by being wound around the exposed portion 110 of the conductive pin 100. More specifically, the winding of the film conductor 65 is started from the portion 130 other than the reduced diameter portion on the front end side in the exposed portion 110 of the conductive pin 100 and finished at the reduced diameter portion 120 on the base end side. Alternatively, the winding of the film conductor 65 is started from the reduced diameter portion 120 on the base end side in the exposed portion 110 of the conductive pin 100 and finished at the portion 130 other than the reduced diameter portion on the front end side. Even when the film conductor 65 is wound in any one of the above procedures, both the property of the portion 130, having corners 131, other than the reduced diameter portion and the property of the reduced diameter portion 120 in which no corners 131 exist can be received.

Next, the procedure for winding the coil in the embodiment will be described with reference to FIGS. 6A to 6D. FIG. 6A is a perspective view of a positional relationship of the conductive pins of the embodiment, and FIGS. 6B to 6D are views provided for explaining how the film conductor is wound around the conductive pin.

As shown in FIG. 6B, the film conductor 65 is wound from the front end portion of a conductive pin 100 a toward the base end side. The winding start portion of the film conductor 65 is the portion 130 other than the reduced diameter portion, and there are the corners 131 (see FIG. 4).

Once the winding of the film conductor 65 is wound up to the reduced diameter portion 120 on the base end side of the conductive pin 100 a, the film conductor 65 is wrapped around a teeth portion 63 of the core stack 62 to form the coil 61. In the reduced diameter portion 120 in which no corners 131 exist, the winding of the film conductor 65 is finished (see FIG. 4), so that the film conductor 65 is laid to the teeth portion 63.

Once wrapping of the coil 61 around the teeth portions 63 of one or two portions is finished, the film conductor 65 is wound around the next conductive pin 100 b, as shown in FIG. 6C. The winding start position, where the film conductor 65 laid from the teeth portion 63 in a preceding process is started to be wound around the conductive pin 100 b, is the reduced diameter portion 120.

Upon completion of winding of the film conductor 65 up to the front end side of the conductive pin 100 b, the film conductor 65 is wound up to the base end of the conductive pin 100 b again. The film conductor 65 wound up to the base end side of the conductive pin 100 b is laid to the next teeth portion 63 to form the coil 61.

Upon completion of the formation of the coils 61 in all the teeth portions 63, the film conductor 65 is wound around a conductive pin 100 c, as shown in FIG. 6D. The film conductor 65 is moved from the base end side of the conductive pin 100 c to the front end side and wound up to the front end, and the winding process is terminated. Since a transition portion from the teeth portion 63 in a preceding process as the winding start of the film conductor 65 is the reduced diameter portion 120 having no corners 131, and the front end as the winding finish of the film conductor 65 is the portion 130, having the corners 131, other than the reduced diameter portion (see FIG. 4).

According to the embodiment, as shown in FIGS. 3 and 4, the conductive pin 100 is in a quadrangular prism shape as a basic configuration. The conductive pin 100 has, in at least a portion of the exposed portion 110 exposed from the electrical insulator 80 of the conductive pin 100, the reduced diameter portion 120 where no corners of the quadrangular prism exist.

Namely, the reduced diameter portion 120 is processed so that the corners are eliminated by crushing, for example. Since the reduced diameter portion 120 has no corners, even if an unexpected load is applied to the film conductor 65 of the coil 61, the film conductor 65 wound around the conductive pin 100 is less likely to be broken.

The portion 130 other than the reduced diameter portion of the exposed portion 110 of the conductive pin 100 has a quadrangular prism shape having the corners 131. Accordingly, the film conductor 65 wound around the conductive pin 100 can be reliably held by the corners 131 of the portion 130 other than the reduced diameter portion.

The reduced diameter portion 120 is positioned at the base end (root) of the exposed portion 110 of the conductive pin 100. Accordingly, the film conductor 65 wound around the reduced diameter portion 120 of the exposed portion 110 is prevented from being shifted from the reduced diameter portion 120 to come out, because the portion 130 on the front end side other than the reduced diameter portion is enlarged to be larger than the reduced diameter portion 120.

By virtue of the use of the corners 131 of the portion 130 other than the reduced diameter portion of the exposed portion 110 of the conductive pin 100, the film conductor 65 having been wound up can be automatically cut by using an automatic winding machine.

Hereinbefore, although the preferred embodiment of the present invention has been described, the embodiment is an example for the purpose of describing the invention, and it is not intended to limit the scope of the invention to only the above embodiment. That is, the invention can be practiced in various aspects different from the above embodiment without departing from the gist of the invention. 

What is claimed is:
 1. An axial flow fan comprising: a stator having coils of a plurality of phases; a rotor having a permanent magnet; and conductive pins each of which is configured to electrically connect the coil and a circuit board and hold a film conductor of the coil, wherein, in the conductive pin, one end is fixed to an electrical insulator covering a core stack of the stator, and the other end is electrically connected to the circuit board, and the conductive pin is a prismatic pin as a basic configuration and has, in at least a part of a portion exposed from the electrical insulator, a reduced diameter portion in which no corners of the prismatic pin exist.
 2. The axial flow fan according to claim 1, wherein the reduced diameter portion is a portion in which a maximum distance in a diameter direction of the conductive pin other than the reduced diameter portion is reduced.
 3. The axial flow fan according to claim 2, wherein the reduced diameter portion has a polygonal shape having an inner diameter more than 90° or a circular shape having no corners.
 4. The axial flow fan according to claim 1, wherein the prismatic pin is in a quadrangular prism shape or a triangular prism shape.
 5. The axial flow fan according to claim 1, wherein the reduced diameter portion is positioned at a base end of the exposed portion in such a state that the conductive pin is fixed to the electrical insulator.
 6. The axial flow fan according to claim 1, wherein the film conductor is held by being wound around the exposed portion of the conductive pin, and winding of the film conductor is started from a portion other than the reduced diameter portion of the exposed portion and finished at the reduced diameter portion, or alternatively, the winding of the film conductor is started from the reduced diameter portion of the exposed portion and finished at a portion other than the reduced diameter portion. 